Electrical Trends In the 70's and 80's

Abstract
More will be expected from the mine or metallurgical plant electrical system in the late 70's and 80's in terms of energy conservation, reliability and fire prevention. Increased electrical loads required by larger arc furnaces, higher-horsepower motors for mine hoists and pollution control fans, and greater use of electrical heating will have to be supplied. Computers and sophisticated instruments will be used more extensively and have less tolerance for electrical fluctuations. More extensive control and monitoring systems will be required to increase production and minimize operating and maintenance costs.Changing energy costs will prompt design engineers to investigate in-plant generation, particularly where sites are remote from existing utilities lines or steam from turbines may be used in the process. Some utilities are requiring industries to increase their power factor to above 90%; others are requiring stricter control of voltage flicker from arc furnaces and harmonics from rectifiers. There is a trend to AC with solid-state controls instead of DC for large cranes.

The first industrial COBO (Cold Bound) pelletizing plant began operation in May 1975 at Trollhattan, Sweden. A technical description of the process, together with operational experience with the plant, forms the basis of this paper.

The basic chemistry of arsenic related to its dissolution and subsequent precipitation in gold-mine waste waters is discussed. The lime addition methods provides the most economic treatment of arsenical slurries, but requires a careful control of the oxidation of As1" into Asv, of the pH (>12) and the filtration of the precipitate. If arsenic levels below 0.5 mg/l are required, a modification of the method by phosphate addition must be considered.

An evaluation of mineralization in the Goosly - Owen Lake area of central British Columbia is the result of a comprehensive geochemical study of rock samples obtained from a regional geological survey. The dispersion of metals in country rocks about a line of Tertiary intrusions suggests that these igneous bodies may be genetically related to known sulphide replacements, dissemination and vein deposits.The geochemical investigation is based on the determination of 12 elements from samples...

Many of the gold deposits in the Timmins area show a close spatial association to ultramafic metavolcanics. Available analytical data suggest that ultramafic rocks contain significantly higher gold contents than other major rock types. In addition, recent analyses by Keays (1975) suggest that talc-carbonate alteration of ultramafic rocks releases significant quantities of gold. It is proposed that the ultramafic volcanics formed the principal source of gold for the deposits in Timmins, and...

Fording Coal Ltd. is now in its fifth year of a 15-year contract to supply S million long tons of clean coal per annum to its Japanese steel-making customers. The mine employs both conventional truck-shovel and unconventional "walking" dragline coal mining techniques in multiple-seam pits.This paper describes the present and future application of the 60-cu.-yd dragline and truck-shovel pre-strip-ping fleet in recovering 5- to 40-foot-thick coal seams in mountainous terrain. Deep blastholes,...

Finance Minister Donald Macdonald's budget of May 25, 1976 featured a restructuring of the anti-inflation profit controls and a grab bag of tax changes, some of direct interest to the mining industry.All Canadian taxpayers now will be permitted to write off immediately 100% of mineral and oil and gas exploration expenses incurred after May 25, 1976 and before July 1, 1979. The cost of acquiring Canadian resource property after May 6, 1974 from, a federal or provincial government will now...

Conventional design criteria assume that the fracture strength of a structural material exceeds its yield strength. Fracture below the design load is not expected, yet many structures have failed in this way. The causes of the fractures are almost always discontinuities such as cracks and welding defects. Linear Elastic Fracture Mechanics (LEFM or simply 'fracture mechanics') provides an analytical framework for assessing the influence of sharp defects on the load-bearing capability of a...

Canada now supplies 23 per cent of the world demand for potash. Although potash is produced by many countries, Russia and Canada have the greatest reserves and capability to supply the future substantial demand over the next decade. It is estimated that demand will grow from 38,000,000 mt KCl in 1975-76 to 60,000,000 mt KCl in 1985-86.Current firm expansion plans and development underway in the world will move Russia to the forefront in supplying this demand growth. Russia will move from...